- Email: [email protected]
Catch effort sampling strategies — Their application in freshwater fisheries management
388
pected oxygen levels that could be found under algal bloom conditions, calm or stormy days and under conditions of cloudy weather. A discussion of the relationship between feed levels and aeration requirements led to a discussion on aerator types and aeration philosophies and management regimes. The infectious disease chapter had subtitles for each major disease which were labeled: clinical signs; characteristics of the disease; transmission, diagnosis and control. This format gives uniformity and adequately covers the main considerations when a farmer is up against a disease problem. The other chapters in the second section provided similar details and gave an excellent cross-section of technology currently in use. I liked the use of simple feed equations whereby the farmer could determine the amount of feed to use by using two or three variables. The final chapter which explored alternative culture systems was most appropriate at a time when the industry is trying to cope with increased pressures for reduced environmental impact of their farming activities and the intensification of production systems to conserve on land and water resources. In summary, the authors did a commendablejob bringing together a broad spectrum of data into a very useable book. The information provided adequately reflects the state-of-the-art presently in use in the US catfish industry. J.P. McVEY
US Department of Commerce National Oceanic and Atmospheric Administration Office of Oceanic Research Programs 1335 East-West Highway Silver Spring, MD 20910 USA
MEASURING FRESHWATER CATCH AND EFFORT
Catch Effort Sampling Strategies m Their Application in Freshwater Fisheries Management. I.G. Cowx (Editor), Fishing News Books, Blackwell Scientific, Oxford, 1991, ix + 420 pp., hard cover, £49.50, ISBN 0-85238-177-8. This book is a report of a symposium organised in 1990 by the European Inland Fisheries Commission to "advance the scientific and management basis of catch effort sampling strategies, and provide a medium for the dissemination and exchange of ideas". Although 31 countries and all continents were represented at the meeting, a strong European bias (24 papers) is evident in the contributions; the continents of South America, Asia and Australasia are each represented by a single paper, and the great amount of work done in North America yields only two papers, although several papers deal with the artisanal fisheries in East African lakes.
389
The contents of the book are not organised in any identified way. Nevertheless, the papers appear to fall into a small number of natural categories and they have been grouped accordingly. The first eight papers deal with salmonid fisheries, mainly for Atlantic salmon in the British Isles; they also include one on a New Zealand river fishcry for trout, and one on lake fisheries for trout in Britain. Most are sport fisheries although some of the rivers also support commercial fisheries for salmon. Some of the papers are only descriptive of data-collecting systems and results, but in several correlations are sought between catches and the actual quantities of fish present. A few papers explore statistical relationships between catch, effort and abundance of fish. Chapters 9-21 form the next group. Nearly all of these deal with recreational fisheries in large still waters in Britain and central Europe. Most are multi-species, non-salmonid fisheries. The data are very variable; they include license returns, competition results, newspaper reports, and surveys of angler opinion. Several papers compare the catch statistics with independent data on the size or composition of the fish populations. A few analyses lead to management recommendations but these rarely take a definite form or have strong foundations in the data. Chapter 19, based on USA experience, reviews the essential steps in the design of catch-effort surveys, under the headings of objectives, data collection, data synthesis and evaluation of results. The other paper of US origin compares a creel survey of a US recreational fishery and a landing point census of an artisanal fishery on a West African river and finds their statistical characteristics to be remarkably similar. The following three chapters return to Europe; two report on the results of surveys to obtain catch and effort data for large lakes perceived to have specific management problems in their commercial fisheries. The third describes studies of the U K sea-bass fishery. Chapters 25-29 deal with more mathematical topics. They include a modelling study on the effect of population distribution on the use of local catch/ unit effort to estimate global populations, an examination of annual variability in the recorded yield of a large number of freshwater fisheries, a critical statistical examination of the characteristics of a proposed survey for an African lake, and a simple method for estimating total annual mortality rate from successive annual age distributions. Also in this section is an account of a system used in the erstwhile USSR to forecast future catches in many commercial lake fisheries. The next group of papers is devoted to catch and catch/unit effort estimation in artisanal lake fisheries; one in Malaysia, the rest in East Africa. In general these show that fairly simple but well organised routine sampling at regular landing places can give information about catches and catch/unit effort which can be used to draw conclusions about the stock that are useful for management purposes.
390
The final chapter contains a review of the main features of the symposium. It considers the objectives for which catch and effort data may be needed in freshwater fisheries, an outline flow-chart of the processes involved in using the data to develop management recommendations, and data collection techniques appropriate to licensed commercial, artisanal and recreational fisheries respectively. The chapter concludes with a set of recommendations as to ways of improving data-collecting systems that were apparently agreed to at the meeting. The book provides a comprehensive picture of the current state of the collection and use of catch and effort data for freshwater fisheries in many parts of the world other than North America. It describes the principal problems encountered in the main categories of fisheries. It shows that in many fisheries, sufficient is being done to reveal trends which can be used to lead to conclusions on which management decisions can be based. In a few cases the results are used to set up surplus yield models that give estimates of available yield, although generally with wide or indeterminate confidence limits. No studies are described which include age-structured models that could give more soundly based estimates. This is perhaps the greatest difference between this book and one which might be written to describe the present state of catch and effort estimation in marine fisheries. The reference lists include only a few citations of research relating to marine fisheries. This is a book which certainly should be in the library of any institution concerned with the development of management policy for freshwater fisheries. I would doubt, however, whether many of the workers there would want to refer to it sufficiently often to require their own copy. Workers in marine fisheries are not likely to have much occasion to need to refer to it. K. RADWAY ALLEN 20/8 Waratah Street Cronulla, N.S. W. Australia
CRUSTACEAN FARMING
Crustacean Farming. Daniel O'C. Lee and John Wickins. Blackwell Scientific, Oxford, 1992, 392 pp., hard back £35, ISBN 0-632-02974-9. My first reaction on the receipt of a work on the farming of crustaceans was perhaps rather an unusual one. I searched (and found) the paragraph on the terminology applicable to shrimps and prawns. My reason for the search was because I am all too frequently summoned to the local Sherriff's Court to assist i n the prosecution of those charged with fishing for salmon with an illegal bait; a 'shrimp or prawn'. Enterprising defence agents are capable of
pected oxygen levels that could be found under algal bloom conditions, calm or stormy days and under conditions of cloudy weather. A discussion of the relationship between feed levels and aeration requirements led to a discussion on aerator types and aeration philosophies and management regimes. The infectious disease chapter had subtitles for each major disease which were labeled: clinical signs; characteristics of the disease; transmission, diagnosis and control. This format gives uniformity and adequately covers the main considerations when a farmer is up against a disease problem. The other chapters in the second section provided similar details and gave an excellent cross-section of technology currently in use. I liked the use of simple feed equations whereby the farmer could determine the amount of feed to use by using two or three variables. The final chapter which explored alternative culture systems was most appropriate at a time when the industry is trying to cope with increased pressures for reduced environmental impact of their farming activities and the intensification of production systems to conserve on land and water resources. In summary, the authors did a commendablejob bringing together a broad spectrum of data into a very useable book. The information provided adequately reflects the state-of-the-art presently in use in the US catfish industry. J.P. McVEY
US Department of Commerce National Oceanic and Atmospheric Administration Office of Oceanic Research Programs 1335 East-West Highway Silver Spring, MD 20910 USA
MEASURING FRESHWATER CATCH AND EFFORT
Catch Effort Sampling Strategies m Their Application in Freshwater Fisheries Management. I.G. Cowx (Editor), Fishing News Books, Blackwell Scientific, Oxford, 1991, ix + 420 pp., hard cover, £49.50, ISBN 0-85238-177-8. This book is a report of a symposium organised in 1990 by the European Inland Fisheries Commission to "advance the scientific and management basis of catch effort sampling strategies, and provide a medium for the dissemination and exchange of ideas". Although 31 countries and all continents were represented at the meeting, a strong European bias (24 papers) is evident in the contributions; the continents of South America, Asia and Australasia are each represented by a single paper, and the great amount of work done in North America yields only two papers, although several papers deal with the artisanal fisheries in East African lakes.
389
The contents of the book are not organised in any identified way. Nevertheless, the papers appear to fall into a small number of natural categories and they have been grouped accordingly. The first eight papers deal with salmonid fisheries, mainly for Atlantic salmon in the British Isles; they also include one on a New Zealand river fishcry for trout, and one on lake fisheries for trout in Britain. Most are sport fisheries although some of the rivers also support commercial fisheries for salmon. Some of the papers are only descriptive of data-collecting systems and results, but in several correlations are sought between catches and the actual quantities of fish present. A few papers explore statistical relationships between catch, effort and abundance of fish. Chapters 9-21 form the next group. Nearly all of these deal with recreational fisheries in large still waters in Britain and central Europe. Most are multi-species, non-salmonid fisheries. The data are very variable; they include license returns, competition results, newspaper reports, and surveys of angler opinion. Several papers compare the catch statistics with independent data on the size or composition of the fish populations. A few analyses lead to management recommendations but these rarely take a definite form or have strong foundations in the data. Chapter 19, based on USA experience, reviews the essential steps in the design of catch-effort surveys, under the headings of objectives, data collection, data synthesis and evaluation of results. The other paper of US origin compares a creel survey of a US recreational fishery and a landing point census of an artisanal fishery on a West African river and finds their statistical characteristics to be remarkably similar. The following three chapters return to Europe; two report on the results of surveys to obtain catch and effort data for large lakes perceived to have specific management problems in their commercial fisheries. The third describes studies of the U K sea-bass fishery. Chapters 25-29 deal with more mathematical topics. They include a modelling study on the effect of population distribution on the use of local catch/ unit effort to estimate global populations, an examination of annual variability in the recorded yield of a large number of freshwater fisheries, a critical statistical examination of the characteristics of a proposed survey for an African lake, and a simple method for estimating total annual mortality rate from successive annual age distributions. Also in this section is an account of a system used in the erstwhile USSR to forecast future catches in many commercial lake fisheries. The next group of papers is devoted to catch and catch/unit effort estimation in artisanal lake fisheries; one in Malaysia, the rest in East Africa. In general these show that fairly simple but well organised routine sampling at regular landing places can give information about catches and catch/unit effort which can be used to draw conclusions about the stock that are useful for management purposes.
390
The final chapter contains a review of the main features of the symposium. It considers the objectives for which catch and effort data may be needed in freshwater fisheries, an outline flow-chart of the processes involved in using the data to develop management recommendations, and data collection techniques appropriate to licensed commercial, artisanal and recreational fisheries respectively. The chapter concludes with a set of recommendations as to ways of improving data-collecting systems that were apparently agreed to at the meeting. The book provides a comprehensive picture of the current state of the collection and use of catch and effort data for freshwater fisheries in many parts of the world other than North America. It describes the principal problems encountered in the main categories of fisheries. It shows that in many fisheries, sufficient is being done to reveal trends which can be used to lead to conclusions on which management decisions can be based. In a few cases the results are used to set up surplus yield models that give estimates of available yield, although generally with wide or indeterminate confidence limits. No studies are described which include age-structured models that could give more soundly based estimates. This is perhaps the greatest difference between this book and one which might be written to describe the present state of catch and effort estimation in marine fisheries. The reference lists include only a few citations of research relating to marine fisheries. This is a book which certainly should be in the library of any institution concerned with the development of management policy for freshwater fisheries. I would doubt, however, whether many of the workers there would want to refer to it sufficiently often to require their own copy. Workers in marine fisheries are not likely to have much occasion to need to refer to it. K. RADWAY ALLEN 20/8 Waratah Street Cronulla, N.S. W. Australia
CRUSTACEAN FARMING
Crustacean Farming. Daniel O'C. Lee and John Wickins. Blackwell Scientific, Oxford, 1992, 392 pp., hard back £35, ISBN 0-632-02974-9. My first reaction on the receipt of a work on the farming of crustaceans was perhaps rather an unusual one. I searched (and found) the paragraph on the terminology applicable to shrimps and prawns. My reason for the search was because I am all too frequently summoned to the local Sherriff's Court to assist i n the prosecution of those charged with fishing for salmon with an illegal bait; a 'shrimp or prawn'. Enterprising defence agents are capable of